In related art, frame structure type 1 (FS1) is adopted by a Long Term Evolution (LTE) Frequency Division Duplexing (FDD) system. In the FDD system, different carrier frequencies are adopted for uplink and downlink transmission, but a same frame structure is adopted for the uplink and downlink transmission. As shown in FIG. 1, on each carrier, a radio frame having a length of 10 ms includes 10 subframes each having a length of 1 ms. Each subframe includes two slots each having a length of 0.5 ms, and a length of a Transmission Time Interval (TTI) for the transmission of uplink and downlink data is 1 ms.
In the related art, a frame structure type 2 (FS2) is adopted by a LTE Time Division Duplexing (TDD) system. In the LTE TDD system, different subframes and slots are adopted for the uplink and downlink transmission at a same frequency. As shown in FIG. 2, in the FS2, each radio frame having a length of 10 ms includes two half-frames each having a length of 5 ms. Each half-frame includes 5 subframes each having a length of 1 ms. There are three types of subframes in the FS2, i.e., downlink subframes, uplink subframes and special subframes. Each special subframe includes a Downlink Pilot Time Slot (DwPTS), a Guard Period (GP) and an Uplink Pilot Time Slot (UpPTS). Each half-frame includes at least one downlink subframe, at least one uplink subframe, and at most one special subframe.
In the related art, the UCI at least includes Acknowledgement (ACK)/Non-Acknowledgement (NACK), Periodic Channel State Information (P-CSI), and a Scheduling Request (SR). The ACK/NACK corresponds to feedback information for downlink transmission (a Physical Downlink Shared Channel (PDSCH) or a Physical Downlink Control Channel (PDCCH)/enhanced PDCCH indicating the release of downlink Semi-Persistent Scheduling (SPS) resources). The P-CSI is adopted to feed back a downlink channel state, so as to enable a base station to schedule the downlink transmission. The SR is adopted to request uplink scheduling, i.e., request the base station to schedule a terminal to transmit a Physical Uplink Shared Channel (PUSCH). These different types of UCIs may be transmitted separately. When a collision occurs for these types of UCIs, a certain type of UCI may be transmitted and another certain type of UCI may be dropped in accordance with a predetermined rule, or several types of UCIs may be transmitted simultaneously. In the related art, the UCI is transmitted on a Physical Uplink Control Channel (PUCCH) having a length of 1 ms. A feedback opportunity of the SR and P-CSI is determined in accordance with a preconfigured period and a preconfigured subframe offset. A feedback period and a subframe offset value are both configured on the basis of subframes, so a minimum feedback opportunity is to perform the feedback within each subframe.
Along with the development of the requirements on the mobile communication services, several organizations, including International Telecommunication Union (ITU), have defined a higher user plane time delay requirement on a future mobile communication system. One of the principal methods for reducing the time delay is to reduce a length of the TTI, so shortened TTI (sTTI) transmission needs to be supported.
For the sTTI transmission, as a typical operating mode, the subframe structure defined in a conventional LTE mechanism includes a plurality of sTTIs each having a length smaller than 1 ms. For the downlink transmission, a shortened PDSCH (sPDSCH) and a shortened PDCCH (sPDCCH) are supported, and for the uplink transmission, a shortened PUSCH (sPUSCH) and a shortened PUCCH (sPUCCH) are supported. The sPUCCH may at least carry the feedback information for the ACK/NACK transmitted in downlink within the sTTI (s-ACK/NACK for short). The terminal which supports the sTTI transmission may have the following features.
The terminal may support dynamic handover between the sPDSCH and the PDSCH. A feedback position of the s-ACK/NACK is determined at least in accordance with the length of the sTTI, and a feedback position of the ACK/NACK transmitted in downlink data transmission within a normal TTI having a length of 1 ms (ACK/NACK for short) is determined at least in accordance with the length of the normal TTI, so the collision may probably occur for the s-ACK/NACK and the ACK/NACK at a same moment (i.e., they need to be fed back at the same moment).
It may be configured to adopt a shorter feedback period for feeding back the P-CSI (s-P-CSI for short) and the SR (s-SR for short), so as to reduce a scheduling time delay. The s-SR is at least adopted to request the scheduling of the sPUSCH. In addition, the terminal which supports the sTTI transmission may also be configured to support the SR to request the scheduling of the PUSCH with the normal TTI length.
The sTTI transmission may be supported separately in the uplink transmission and the downlink transmission. In other words, the time delay is strictly required for the downlink transmission while the time delay is not required for the uplink transmission, the sTTI transmission may be merely adopted in the downlink transmission, and vice versa.
In the above cases, various combination collisions may probably occur between different types of shortened UCIs (sUCIs), and various combination collisions may probably occur between the sUCI and the UCI. However, there is currently no definite method for transmitting the sUCI and the UCI in the case of the collisions, so the reliability of the network communication may be adversely affected.